The present invention relates to a micro device using a micro electro mechanical system (MEMS) technology, and more particularly, to a condenser-type MEMS microphone.
Microphones are apparatuses for converting voices into electrical signals. In recent, as the development of wire-wireless equipment is accelerated, a microphone is gradually decreasing in size. Thus, microphones using MEMSs have been developed in recent years.
Such a microphone may be largely classified into a piezo-type microphone and a condenser-type microphone. The piezo-type microphone may use a piezo effect in which a potential difference occurs between both ends of a piezo-electric material when a physical pressure is applied to the piezo-electric material. Here, a pressure of a voice signal may be converted into an electrical signal. The piezo-type microphone has many limitations in application due to a low bandwidth and a uniform characteristic of a voice band frequency. The condenser-type microphone may use a principle of a condenser of which two electrodes face each other. Here, one electrode of the microphone may be fixed, and the other electrode may serve as a diaphragm. This is, when the diaphragm is vibrated by a pressure of a voice signal, a capacitance between the two electrodes may be changed to change a condensed charge, and thus, current may flow. The condenser-type microphone may have stability and superior frequency characteristic. Thus, the condenser-type microphone is being widely used as the microphone.